I am working on modling expected outcomes when one partner passes before the other.

I know that expenses do not halve when a partner passes, but realistically only decrease by ~15%

Is there currently any way that MRA can automatically account for that in its modeling?

Joint expenses are inherited in full by the surviving spouse, whereas they disappear at the death of their owner when not Joint.

So it's kind of all or nothing right now.

I do like your suggestion. It's just more questions to ask the user.

My work around is to add individual expenses, with mine being 85% of the total and my wifes beign 15%, then in the modeling, the overall expesnses are reduced when she passes.

(Putting this in words is unsettling, but this is the reality of our lifes!)

Well yes, you can add as many individual expenses as you like, starting and ending at any date, that's always there. 

Having an increase/decrease% starting linked to a date/event, would be a convenience feature I would add, if I can make it easy.

I appreciate what you're going through running these scenarios. It is unsettling, and unfortunately, a necessary part of financial planning.

My advice: don't tell your spouse you are doing this unless you are working with them on it. At least for my spouse, the "I killed myself off early in the TIME MACHINE today, and you'll be fine!" didn't go over as well as I thought it would 😀